Sandpaper with laminated non-slip layer

ABSTRACT

A sheet of sandpaper includes a backing layer having opposed first and second major sides, an adhesive make coat on the second major side, abrasive particles at least partially embedded in the make coat, thereby defining an abrasive surface, and an exposed laminated non-slip layer on the first major side. Methods of making and using such sandpaper are also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 61/498,673, filed Jun. 20, 2011, the disclosure of whichis incorporated by reference herein in its entirety.

BACKGROUND

The present invention relates generally to abrasive articles forabrading a work surface such as, for example, flexible sheet-likeabrasive articles.

Sheet-like abrasive articles are commonly used in a variety of sandingoperations including, for example, hand sanding of wooden surfaces. Inhand sanding, the user holds the abrasive article directly in his or herhand and moves the abrasive article across the work surface. Sanding byhand can, of course, be an arduous task.

Sheet-like abrasive articles include, for example, conventionalsandpaper. Conventional sandpaper is typically produced by affixingabrasive material to a relatively thin, generally non-extensible,non-resilient, non-porous backing (e.g., paper). The thin, flat,slippery nature of conventional sandpaper backing materials makesconventional sandpaper difficult to grasp, hold, and maneuver. Becauseof the slippery nature of conventional sandpaper, to hold a sheet ofsandpaper securely, a user will grasp the sheet of sandpaper between hisor her thumb and one or more of his or her remaining fingers. Holdingthe sandpaper in this manner is uncomfortable, can lead to muscle crampsand fatigue, and is difficult to maintain for an extended period oftime. In addition, the thumb is typically in contact with the abrasivesurface of the sandpaper, which can irritate or damage the skin. Also,because the thumb is positioned between the sandpaper and the worksurface, grasping the sandpaper in this manner also interferes with thesanding operation. That is, due to the position of the thumb, a portionof the sandpaper abrasive surface is lifted away from the work surfaceduring sanding. Because the lifted portion is not in contact with thework surface, the full sanding surface of the sandpaper is not utilized,and the effectiveness of the sandpaper is, therefore, diminished.

During hand sanding, a user often applies pressure to the sandpaperusing his or her fingertips. Because of the thin nature of the backingmaterials used in conventional sandpaper, the finger pressure isconcentrated in the regions where the finger pressure is applied. This,in turn, causes the sandpaper to wear and/or load unevenly, and producesan uneven sanding pattern on the work surface.

Conventional sandpaper is typically sold in standard size sheets, suchas 9×11 inch sheets. To make sandpaper easier to use, users often foldthe sandpaper, thereby producing smaller sheets that are easier tohandle. Folding the sandpaper, however, produces a jagged edge, and alsoweakens the sandpaper along the fold line. During the rigors of sanding,the weakened fold line may tear, thereby resulting in premature failureof the sandpaper.

SUMMARY

A sheet of sandpaper includes a backing layer having opposed first andsecond major sides, an adhesive make coat on the second major side,abrasive particles at least partially embedded in the make coat, therebydefining an abrasive surface, and an exposed laminated non-slip layer onthe first major side. Methods of making and using such sandpaper arealso provided.

In one aspect, disclosed herein is a sheet of sandpaper, comprising: aflexible backing layer having opposed first and second major sides; anadhesive make coat on the second major side of the backing layer;abrasive particles at least partially embedded in the make coat, therebydefining an abrasive surface; and an exposed laminated non-slip layer ofless than about 600 microns in thickness, on the first major side of thebacking layer.

In another aspect, disclosed herein is a method of making a sheet ofsandpaper having a laminated non-slip layer on the first major sidethereof, comprising the steps of: providing a flexible backing layerhaving opposed first and second major sides; coating an adhesive makecoat on the second major side of the backing layer; at least partiallyembedding abrasive particles in the make coat, thereby forming anabrasive surface; and, laminating a non-slip layer onto the first majorside of the backing layer to form an exposed laminated non-slip layer ofless than about 600 microns in thickness on the first major side of thebacking layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described with reference to theaccompanying drawings, in which:

FIG. 1 is a cross sectional view of an exemplary sheet of sandpaperaccording to the invention.

FIG. 2 is a cross sectional view of an exemplary particular embodimentof a sheet of sandpaper.

FIG. 3 is a cross sectional view of another exemplary particularembodiment of a sheet of sandpaper.

FIG. 4 is a cross sectional view of another exemplary particularembodiment of a sheet of sandpaper.

FIG. 5 is a cross sectional view of another exemplary particularembodiment of a sheet of sandpaper.

FIG. 6 is a cross sectional view of another exemplary particularembodiment of a sheet of sandpaper.

DETAILED DESCRIPTION

Referring now to the drawings, FIG. 1 shows in exemplary genericrepresentation a flexible sheet-like abrasive article 10, such as asheet of sandpaper. As used herein, the expression “sheet-like” refersgenerally to the broad, thin, flexible nature of abrasive article 10.Article 10 comprises a flexible backing layer 12 having opposed firstand second major sides respectively bearing first 12 a and second 12 bmajor surfaces, and comprises an exposed laminated non-slip layer 14 onthe first major side of backing layer 12, an adhesive make coat layer 16on the second major side of backing layer 12, and a plurality ofabrasive particles 18 at least partially embedded in the make coat layer16. (The terms first major side (and e.g. first major surface thereof)will in general denote the side and surface of backing 12 bearinglaminated non-slip layer 14 (i.e., the side opposite abrasive particles18), and the terms second major side (and e.g. second major surfacethereof) will in general denote the side and surface of backing 12thereof comprising abrasive particles 18.) The condition that laminatednon-slip layer 14 is “on” the first major side of backing layer 12 (aswell as the act of laminating non-slip layer 14 “on” or “onto” the firstmajor side of backing layer 12) encompasses both cases in which layer 14(e.g., major surface 14 b of layer 14) is in direct contact with majorsurface 12 a of the first major side of layer 12, and cases in whichlayer 14 is separated from direct contact with major surface 12 a, e.g.by one or more adhesion-enhancing layers and/or support layers asdisclosed later herein.

As used herein, the term laminated non-slip layer denotes a non-sliplayer (optionally along with other layers as disclosed herein) thatexists in a pre-formed condition (e.g., as a film, nonwoven web, etc.)with a pre-existing thickness and that is delivered to the first majorside of backing 12 in this pre-formed condition and is laminated (e.g.,bonded, e.g. by use of heat and/or pressure) directly or indirectly tothe first major side of backing 12. A laminated non-slip layer thus doesnot encompass a coated layer that is achieved by depositing a layer offlowable material onto the first major side of backing 12 andsolidifying the material to form the coated layer in such manner thatthe deposition and/or solidification process determines the thickness ofthe coated layer. As used herein, the expression “layer” denotes thatthe laminated layer of non-slip material is in the form of a discretestratum on backing layer 12 (i.e. the non-slip material does not soakthrough the entire thickness of the backing layer 12). In someembodiments, laminated non-slip layer 14 consists of a single layer ofnon-slip material (optionally with one or more layers of other materialbeing present between laminated non-slip layer 14 and backing 12).

In some embodiments, laminated non-slip layer 14 (e.g., major surface 14b of layer 14) may be in direct contact with first major surface 12 a ofbacking layer 12 (as shown in generic representation in FIG. 1 and in aspecific exemplary embodiment in FIGS. 4 and 6). In other embodiments,one or more optional intermediate layers of material may be presentbetween backing layer 12 and laminated non-slip layer 14 (as shown inexemplary specific embodiments in FIGS. 2, 3 and 5), for variouspurposes as disclosed herein. Such intermediate layers may comprise e.g.support layers and/or adhesion-enhancing layers. In various embodiments,such intermediate layers may comprise an average thickness of less thanabout 200 microns, less than about 100 microns, less than about 50microns, less than about 25 microns, or less than about 10 microns, andmay be applied by any suitable method including e.g. by coating, vapordeposition, etc. Such intermediate layers may be continuous ordiscontinuous. In some embodiments such intermediate layers may becomprised of dense materials (e.g., lacking porosity). Such intermediatelayers do not encompass layers such as sponge layers, foam layers,synthetic microporous membrane layers, and the like.

Laminated non-slip layer 14 is an exposed layer. By this is meant thatouter surface 14 a of laminated non-slip layer 14 is an exposed surfacethat makes up at least the majority of the outermost surface of thefirst major side of abrasive article 10 when article 10 is in use. Thatis, the majority of outer surface 14 a of article 10, as article 10 isprovided to an end user, is not covered, buried, or obscured by anyother layer, except for, optionally, such items as labels, stickers,price tags, temporary protective sheets or liners, or the like, whichare not permanently attached to laminated non-slip layer 14 and whichmay be removed if desired prior to use of article 10. Thus, a laminatedlayer which bears a further-outward permanently attached layer (e.g., ahook layer, a loop layer, a mechanical fastening layer, apressure-sensitive adhesive layer, etc.) over a majority of its area, bydefinition does not comprise an exposed laminated non-slip layerirrespective of the composition and/or properties of the laminatedlayer. In various embodiments, at least about 50%, at least about 75%,or at least about 90%, of outer surface 14 a of non-slip layer 14 is anexposed surface. In some embodiments, the entirety of outer surface 14 aof laminated non-slip layer consists of an exposed surface.

As used herein, “non-slip” layers refer to layers that increase thecoefficient of friction of the backing layer surface to which thenon-slip material is applied. That is, if the surface of the backinglayer 12 a to which a laminated non-slip layer is applied has acoefficient of friction of “x” prior to when the layer is laminatedthereon, and the laminated layer—as applied to the surface of thebacking—provides a surface that has a coefficient of friction that isgreater than “x”, then the layer is a “non-slip” layer. Or statedanother way, if the laminated layer tends to increase the coefficient offriction of the backing surface to which it is applied, then thelaminated layer qualifies as a “non-slip” layer.

In one embodiment, the laminated non-slip layer 14 has an average peakstatic coefficient of friction of at least about 1.0 gram, at leastabout 1.25 grams, or at least about 1.5 grams when measured according toASTM D 1894-08 (Standard Test Method for Static and Kinetic Coefficientsof Friction of Plastic Film and Sheeting) at 23° C. using an IMASSslip/peel tester (SP2000, commercially available from InstrumentorsInc., Strongsville, Ohio), and/or an average kinetic coefficient offriction of at least about 0.75 grams, at least about 1 gram, or atleast about 1.25 grams.

In various embodiments, laminated non-slip layer 14 outer surface 14 amay have no tack, or may have a low level of tack. If the non-slip layeris tacky, it may be desirable that the tack be kept to a low level. Bylow level of tack, it is meant that the non-slip layer has an averagetack level, as measured by ASTM D2979-88 (Standard Test Method for Tackof Pressure-Sensitive Adhesives Using an Inverted Probe Machine) using aten (10) second dwell time, and a probe removal speed of one (1) cm/s,of no greater than about 350 grams. A non-slip layer as defined anddisclosed herein (even if it comprises a low level of tack, as opposedto no tack), comprises a sufficiently low level of tack that bydefinition it may not be equated with conventional pressure-sensitiveadhesives e.g. as may sometimes be used to attach sandpaper to sandingblocks, vibrating or orbital sanders, and the like. In variousembodiments, laminated non-slip layer 14 has an average tack level, asmeasured by ASTM D2979-88 (Standard Test Method for Tack ofPressure-Sensitive Adhesives Using an Inverted Probe Machine) using aten (10) second dwell time, and a probe removal speed of one (1) cm/s,of no greater than about 200 grams, no greater than about 250 grams, orno greater than about 300 grams.

In some embodiments, laminated non-slip layer 14 may comprise anadhesion to itself that is less than the cohesive strength of thenon-slip layer itself, and further may have an adhesion to itself thatis less than the “two-bond” adhesive strength. As is known to thoseskilled in the art, the “two-bond” adhesive strength is the adhesivestrength between non-slip layer 14 and backing layer 12 to which thelaminated non-slip layer is applied. Thus, when non-slip layer 14 isfolded over onto itself, the areas of the surface of the non-slip layerthat come into contact with each other can be released from each otherwithout experiencing cohesive failure of the non-slip layers, andwithout having any portion of laminated non-slip layer 14 detach frombacking layer 12.

In some embodiments, the non-slip layer provides a surface that may berepeatably bonded to itself. In another somewhat related aspect,non-slip layer 14 may be repositionable. As used herein,“repositionable” refers to a non-slip layer that allows repeatedapplication, removal, and reapplication to and from itself or a surfacewithout damage to the non-slip layer or the surface.

In addition, it is desirable that the adhesion of laminated non-sliplayer 14 to itself not build significantly over time. As such, ifabrasive article 10 is folded over onto itself such that areas of thesurface of the non-slip layer come into contact with each other,abrasive article 10 may later be readily unfolded by separating thecontacted surface areas of laminated non-slip layer 14 without damagingnon-slip layer 14 or backing layer 12.

In various embodiments, the laminated non-slip layer may have a glasstransition temperature of at least about −80 degrees Celsius (° C.), atleast about −70° C., and at least about −65° C., and a glass transitiontemperature of no greater than about −5° C., no greater than about −15°C., and no greater than about −25° C.

In various embodiments, laminated non-slip layer 14 may comprise athickness (e.g., an average thickness as measured in several locations)of at least about 10 microns, at least about 15 microns, at least about20 microns, or at least about 25 microns. In further embodiments,laminated non-slip layer 14 may comprise a thickness of at most about800 microns, at most about 400 microns, at most about 200 microns, atmost about 100 microns, at most about 50 microns, or at most about 40microns.

In various embodiments, laminated non-slip layer 14 may comprise anareal density (e.g., an average as measured in several locations) of atleast about 10 grams per square meter, at least about 15 grams persquare meter, at least about 20 grams per square meter, or at leastabout 25 grams per square meter. In further embodiments, laminatednon-slip layer 14 may comprise an areal density of at most about 200grams per square meter, at most about 100 grams per square meter, atmost about 60 grams per square meter, or at most about 25 grams persquare meter. In various embodiments, the material of laminated non-sliplayer 14 may comprise a volumetric density of at least about 0.9grams/cc, at least about 0.95 grams/cc, or at least about 1.0 grams/cc.

In some embodiments, laminated non-slip layer 14 may be comprised of anessentially dense material (e.g., without any microscopic porosity orinternal void volume other than the occasional voids, free volume, etc.,as are known to those of skill in the art to be sometimes present inmany polymeric materials), irrespective of any macroscopicdiscontinuities (e.g., through-holes or the like) that may be present insome embodiments. In some embodiments, laminated non-slip layer 14 maybe comprised of a fibrous material such as e.g. a nonwoven fibrous layersuch as a spunbonded web, a meltblown web, or a carded web; a woven web;a knitted cloth; a polymeric netting; or the like. Laminated non-sliplayer 14 of an abrasive article 10 (e.g. sandpaper), as disclosedherein, does not encompass a sponge or foam layer, whether open orclosed cell (e.g., of a so-called sanding sponge).

Laminated non-slip layer 14 may be continuous or discontinuous, with theterm discontinuous signifying the presence of macroscopic (e.g., with adimension of greater than about 100 microns) features such asthrough-holes and the like. Such through-holes may comprise e.g.generally straight-through passages achieved by perforation, punching orthe like, or may be in the form of somewhat tortuous passages of thetype that may be naturally present e.g. when laminated non-slip layer 14is in the form of a nonwoven fibrous material. In various embodiments,such discontinuities may be present regular and/or repeating patterns,in random, irregular or non-repeating patterns, or in any combination ofsuch patterns.

As mentioned, and as pictured in the embodiment illustrated in FIG. 1,non-slip layer 14 defines an outer surface 14 a on the first major sideof article 10, opposite make coat 16 and abrasive particles 18. In someembodiments outer surface 14 a may be a generally planar surface that bydefinition does not include a textured pattern or a visually observablethree dimensional surface topography. In other embodiments, the outersurface of non-slip layer 14 may comprise a textured or patternedsurface. This might be achieved e.g. by manufacturing layer 14 in suchmanner as to impart a non-smooth outer surface. Or, laminated non-sliplayer 14 may comprise filler material or particles to provide thelaminated non-slip layer 14 outer surface 14 a with a rough or randomlytextured surface. Such a rough, textured or patterned surface may serveto enhance the non-slip properties of laminated non-slip layer 14.

In some embodiments, laminated non-slip layer 14 may be clear. In thismanner, any information or indicia printed on backing layer 12 willremain visible through laminated non-slip layer 14. In addition, theappearance of the sandpaper may remain similar to the appearance ofconventional sandpaper, to which users have become accustomed. In otherembodiments, laminated non-slip layer 14 may be colored, pigmented,etc., for any effect as desired. In some embodiments, laminated non-sliplayer 14 is permanently bonded to backing 12 (either directly to surface12 a of backing 12, or via one or more intermediate layers as discussedherein).

In some embodiments, laminated non-slip layer 14 may comprise at leastone base resin. A base resin may comprise any suitable polymericmaterial that provides mechanical integrity and toughness to thenon-slip layer, but that may not necessarily (in the absence of thetackifying resin) supply the desired non-slip properties disclosedherein. Suitable base resins for non-slip layer 14 may include, forexample: natural and synthetic rubbers such as synthetic polyisoprene,butyl rubbers, polybutadiene, styrene-butadiene rubber (SBR),carboxylated styrene-butadiene rubber, block copolymers such as Kratonrubber, polystyrene-polyisoprene-polystyrene (SIS) rubber,styrene-butadiene-styrene (SBS) rubber, nitrile rubber (Buna-N rubbers),hydrogenated nitrile rubbers, acrylonitrile-butadiene rubber (NBR),chloroprene rubber, polychloroprene, neoprene, EPM rubber (ethylenepropylene rubber), EPDM rubber (ethylene propylene diene rubber),ethylene-propylene-butylene terpolymers, acrylic rubber, polyacrylicrubber, silicone rubber; copolymers such as ethylene-vinyl acetate (EVA)copolymers, ethylene-(meth)acrylate copolymers, ethylene-vinylacetate-maleic anhydride and/or ethylene-(meth)acrylate-maleic anhydrideterpolymers; and other polymeric materials such as polyvinyl acetates,grafted polyvinyl acetates or EVA copolymers, polyamides, polyesters,thermoplastic elastomers, thermoplastic vulcanizates such as Santoprenethermoplastic rubber, thermoplastic polyurethanes, and thermoplasticolefins and amorphous polyolefins.

In some embodiments, the at least one base resin may comprise apoly(vinyl ether) polymer, e.g. an amorphous poly(alkyl vinyl ether)polymer such as amorphous poly(methyl vinyl ether). In some embodiments,the at least one base resin may comprise a polyolefin, e.g. apolyethylene, polypropylene, polybutene, and/or copolymers (includingterpolymers) thereof. In certain embodiments, such a polyolefin maycomprise a grafted polyolefin, e.g. a polyethylene with a saponificationnumber of at least three, and which may be grafted e.g. withpolycarboxylic acids, anyhydrides, esters thereof, or the like. Incertain other embodiments, such a polyolefin may comprise a metallocene(catalyzed) polyolefin, for example a functionalized metallocenepolyethylene polymer or copolymer. Such polymers or copolymers may befunctionalized e.g. with acids such as acrylic acid, acetates,sulfonates, maleic anhydrides, or the like.

In some embodiments, the base resin may comprise an amorphous polymer.By amorphous is meant a polymer that displays essentially nocrystallinity, as evidenced by no, or at most a very weak (i.e., barelydiscernible), melting point(s) on a Differential Scanning calorimetrycurve, as will be appreciated by those of ordinary skill. In variousspecific embodiments, an amorphous polymer may comprise an amorphoushydrocarbon polymer or copolymer (such as, e.g., polyolefin polymersand/or copolymers containing ethylene, propylene, higher alkenes, and/orcopolymers thereof, polymers and/or copolymers of higher order dienes,polymers and/or copolymers of poly-alpha olefins, etc.); or, anamorphous heteroatom polymer or copolymer (such as, e.g.polyolefin-poly(meth)acrylate copolymers, polyolefin-EVA copolymers,poly(vinyl ether) polymers and/or copolymers, and the like). In someembodiments, the amorphous polymer may comprise atactic polypropyleneand/or copolymers thereof. In some embodiments, the amorphous polymer isan aliphatic polymer (i.e., not comprising aromatic units). In someembodiments, the base resin consists essentially of an amorphous polymeror copolymer or of mixtures of amorphous polymers or copolymers. In someembodiments, the amorphous polymer may comprise a poly-alpha-olefinhydrocarbon copolymer (e.g., terpolymer) containing propyl, ethyl, andbutyl monomer units (e.g., obtained by the copolymerization ofpropylene, ethylene, and 1-butene). In particular embodiments, theamorphous polymer may comprise, or may consist essentially of, apropylene-rich poly-alpha-olefin polymer, meaning a copolymer containingat least about 70 mole % of propylene-derived monomer units and fromabout 5 mole % to about 15 mole % of 1-butene-derived monomer units,with the balance being chosen from any other suitable monomer units,e.g. ethylene.

The above list is meant to be representative, not exhaustive. Blends,mixtures, etc. of any of the above base resins may be used if desired.

In some embodiments, laminated non-slip layer 14 may comprise aneffective amount of at least one tackifying resin. A tackifying resinmay comprise any material (e.g., polymeric material) that may notnecessarily comprise acceptable mechanical integrity by itself, but thatwhen present at an effective amount along with a base resin, suppliesthe combination of resins with the desired non-slip properties disclosedherein. By an effective amount of tackifying resin is meant an amountsufficient to satisfactorily provide the non-slip properties disclosedherein (e.g., whether measured quantitatively by way of a coefficient offriction and/or tack test as disclosed earlier herein, or qualitativelyby way of manually handling and sanding with an abrasive articlecomprising the non-slip layer). By an effective amount is further meantan amount that is lower than a threshold level that would cause thenon-slip layer to be a conventional pressure-sensitive adhesive.

Suitable tackifying resins for non-slip layer 14 may include, forexample: polymeric terpenes, hetero-functional terpenes,coumarone-indene resins, rosin acids, esters of rosin acids,disproportionated rosin acid esters, hydrogenated rosin acids, C₅aliphatic resins, C₉ aromatics, C₉ hydrogenated aromatic resins, C₅/C₉aliphatic/aromatic resins, dicyclopentadiene resins, hydrogenated pinenepolymers or copolymers, hydrogenated hydrocarbon resins arising fromC₅/C₉ and dicyclopentadiene precursors, hydrogenated styrene monomerresins, alpha-methyl styrene resins, hydrogenated mixed aromatictackifying resins, aliphatic/aromatic hydrocarbon liquid tackifyingresins; napthenic oils, mineral oils, alkyl phenolic tackifying resins,and the like. Additionally potentially suitable tackifying resins mayinclude, for example: alpha-methylstyrene; copolymers ofalpha-methylstyrene and styrene; hydrogenated cyclopentadienes, a rosinor a terpene resin of the alpha-pinene, beta-pinene and d-limonenetypes; wood rosins or gum rosins; rosin esters derived from either gumor wood rosin, such as glycerol esters (ester gums), pentaerythritolesters, hydrogenated, polymerized or disproportionated gum or woodrosins; polyhydric alcohol derivatives of hydrogenated rosin, such asglycerol derivatives or polyhydroalcohol derivatives of polymerizedrosins; e.g. ethylene glycol ester, glycerol esters, oxidized rosins,hydrogenated oxidized rosin esters of oxidized rosin and the like. Stillother potentially suitable tackifying resins may include e.g.hydrocarbon resins such as polyterpenes, synthetic polyterpenes, andthose materials obtained from the polymerization of olefins anddiolefins (e.g., the aliphatic olefin derived tackifying resinsavailable from the Sartomer Company of Exton, Pa. under the tradedesignation Wingtack). Still other potentially suitable tackifyingresins include e.g. terpene polymers such as the polymeric, resinousmaterials obtained by polymerization and/or copolymerization of terpenehydrocarbons such as the alicyclic, monocyclic, and bicyclicmonoterpenes and their mixtures, including allo-ocimene, carene,isomerized pinene, pinene, dipentene, terpinene, terpinolene, limonene,turpentine, a terpene cut or fraction, and various other terpenes. Insome embodiments, the tackifying resin(s) is a hydrocarbon material; inparticular embodiments, the tackifying resin(s) is an aliphatichydrocarbon material. Such materials may be e.g. branched hydrocarbonpolymers.

This list is meant to be representative, not exhaustive. Blends,mixtures, etc., of any or all of the above-listed tackifying resins canbe used.

Laminated non-slip layer 14 may optionally comprise at least one wax, bywhich is meant a relatively low molecular weight material that maymodify or enhance various properties of the laminated non-slip layer.Any suitable natural (e.g., animal, vegetable, mineral, or petroleumbased) or synthetic wax may be used. Such waxes may include e.g.hydrocarbon waxes, paraffin waxes, microcrystalline waxes, fatty amidewaxes, hydroxy stearamide waxes, vinyl acetate-modified waxes, maleicanhydride-modified waxes, high density low molecular weight (e.g., lessthan approximately 2500) polyethylene waxes, and the like.

Any other desirable ingredients may be included in laminated non-sliplayer 14 as long as they do not unacceptably affect the non-slipproperty. Such additives may include e.g. processing aids, extrusionaids, antioxidants, wetting agents, UV stabilizers, nucleating agents,plasticizers, pigments, dyes, fillers, and so on.

In some embodiments, laminated non-slip layer 14 consists essentially ofat least one base resin, at least one tackifying resin, and at least onewax along with optional minor quantities of additives such as processingaids, antioxidants and the like.

In some embodiments, laminated non-slip layer 14 may be bonded directlyto backing 12 with no other layer(s) therebetween; i.e., major surface14 b of layer 14 may be bonded directly to major surface 12 a of backing12. In such cases, at least major surface 14 b of non-slip layer 14 maycomprise a composition capable of bonding to major surface 12 a. Forexample, non-slip layer 14 may comprise e.g. a heat-bondablecomposition, e.g. may be a thermoactivatable web (which term encompassesboth dense films, and porous materials such as nonwoven webs, nettingand the like). Thermoactivatable webs are generally known, and mayinclude e.g. products available from ProTechnics, Cernay, France, underthe trade name Texiron. Any thermoactivatable web may be used as long asit satisfies the conditions prescribed earlier herein (i.e., that layer14 possesses suitable non-slip properties).

Configurations in which laminated non-slip layer 14 may be bondeddirectly to backing 12 are shown in generic exemplary representation inFIG. 1 and in a particular exemplary configuration in FIG. 4, discussedlater herein.

In other embodiments, one or more intermediate layers of other materialmay be present between at least a portion of non-slip layer 14 and atleast a portion of backing 12. In particular embodiments, such a layeror layers are present between the entirety of non-slip layer 14 andbacking 12. In some embodiments, such intermediate layers may compriseadhesion-enhancing layers, which category broadly encompasses any layerwhich provides, facilitates, promotes, etc., the bonding of non-sliplayer 14 to backing 12.

In a particular exemplary embodiment depicted in FIG. 2,adhesion-enhancing layer 20 comprises an adhesive layer that is capableof bonding both to major surface 14 b of non-slip layer 14, and to majorsurface 12 a of backing 12. Such an adhesive layer may be comprised ofany suitable adhesive composition, delivered to article 10 by anysuitable mechanism. In some embodiments, adhesive layer 20 may be alaminating adhesive, e.g. a pressure-sensitive adhesive. In specificembodiments, adhesive layer 20 may comprise a hot-melt adhesivecomposition which may be deposited onto the backside of backing 12 in aheated (flowable) state, with non-slip layer 14 being brought intocontact with an exposed surface of adhesive layer 20 e.g. while layer 20is still in a heated state in which it is capable of bonding to non-sliplayer 14. In such manner, non-slip layer 14 can be laminated to backing12. In other embodiments, adhesive layer 20 may comprise a pre-formedlayer (e.g., film or web) which may be placed in between backing 12 andnon-slip layer 14 and heated so as to activate or promote bondingbetween the major surfaces of adhesive layer 20 and the major surfacesof backing 12 and non-slip layer 14. Various thermoactivatable webs maybe useful for such purposes, including e.g. products available fromProTechnics, Cernay, France, under the trade name Texiron (noting thatin this particular configuration a thermoactivatable web, not serving asa non-slip layer itself, may not necessarily need to satisfy anyparticular non-slip criterion). It should be noted that adhesive layer20 does not necessarily need to be a continuous layer, and can comprisesuch adhesive materials as may be discontinuously deposited (e.g.,sprayed) onto the first major side of backing 12.

In further detail, adhesive layer 20 may comprise e.g. any of apressure-sensitive adhesive, a hot-melt adhesive, a hardenable adhesive,a drying adhesive, and a photohardenable adhesive (recognizing that someadhesive compositions may fall into more than one of these categories).By a hardenable adhesive is meant an adhesive that solidifies by achemical reaction (with or without liberation of small molecules), e.g.a moisture-cure silicone, an epoxy, and the like. By a drying adhesiveis mean an adhesive that solidifies by the loss of a solvent and/orwater, e.g. rubber cement, a water-based glue, and the like. By aphotohardenable adhesive is meant one whose hardening is initiated orpromoted by radiation (such as visible light, UV radiation, etc.), e.g.the well-known UV-curable adhesives and the like.

In other embodiments, adhesion-enhancing layer 20 may comprise anadhesion-promoting layer, e.g. a tie layer, primer layer, or the like,that is deposited, coated, or otherwise formed atop major surface 12 aof backing 12. The composition of such an adhesion-promoting layer maybe chosen in view of the composition of non-slip layer 14 which isdesired to be laminated to backing 12. For example, if non-slip layer 14comprises polyolefin components, a primer or tie layer may be disposed(e.g. coated) onto major surface 12 a of backing 12, that promotesbonding to such polyolefin components. More than one adhesion-enhancinglayer, of any desired type, may be used, e.g. in combination. Forexample, upon selecting a laminating adhesive that is well suited tobond to a particular laminated non-slip layer 14, a tie layer may becoated onto major surface 12 a of backing 12, that is particularlysuited to be bonded by that same laminating adhesive. It should be notedthat, like an adhesive layer, an adhesion-promoting layer may or may notbe a continuous layer.

As illustrated in exemplary manner in FIG. 3, one or more support layers24 may be provided in between at least a portion of laminated non-sliplayer 14 and a portion of backing 12. Such a support layer may beparticularly useful in a case in which non-slip layer 14 is sufficientlythin, and/or comprises sufficiently delicate physical properties, as tomake non-slip layer 14 difficult to handle as a free-standing film orweb. In such circumstances, non-slip layer 14 may be provided on supportlayer 24 which becomes part of the structure of the resulting article10. As such, a support layer 24 is defined herein as a layer upon whichnon-slip layer 14 is already bonded to form a multilayer structure,prior to layer 14 being laminated onto the first major side of backing12. In the exemplary embodiment of FIG. 3, article 10 comprises supportlayer 24 on which non-slip layer 14 is provided without the material ofnon-slip layer 14 penetrating substantially into support layer 24. Forexample, non-slip layer 14 may comprise a hot-melt-coatable compositionthat is coated onto surface 24 a of support layer 24. Thehot-melt-coatable composition may then be cooled to form non-slip layer14 (e.g., prior to rolling up the multilayer construction of supportlayer 24 and non-slip layer 14). Then, support layer 24 (bearingnon-slip layer 14 thereupon) may be laminated to backing layer 12. Inexemplary embodiments of the general type depicted in FIG. 3, anadhesion-enhancing layer 20 (e.g., a laminating adhesive) may be used tobond support layer 24 to backing 12. In some embodiments, support layer24 may also function as an adhesion-enhancing layer, in which case aseparate adhesion-enhancing layer 20 may not necessarily be needed.

If a support layer 24 is used, its composition may be chosen so thatnon-slip layer 14 may be adhered satisfactorily to major surface 24 a ofsupport layer 24. If desired, major surface 24 a may be treated, and/ora tie layer applied, so as to enhance the ability of non-slip layer 14to remain adhered to support layer 24. Likewise, if anadhesion-enhancing layer 20 is used to bond support layer 24 to thefirst major side of backing layer 12, surface 24 b of support layer 24may be treated so as to enhance its ability to be bonded byadhesion-enhancing layer 20.

Support layer 24 may be comprised of any suitable web, encompassing bothdense materials (e.g., films) and discontinuous (e.g., porous) webs(e.g. nonwovens and the like), that has adequate physical properties torender a multilayer combination of support layer 24 and non-slip layer14 able to be handled so as to be laminated to backing 12. For example,support layer 24 may comprise a film of polyester, polyethylene,polypropylene (e.g., oriented or biaxially oriented polypropylene),cellophane, or the like. The thickness of support layer 24 may belikewise chosen to provide sufficient handleability to the multilayercombination of support layer 24, and non-slip layer 14, while preservingacceptable flexibility of abrasive article 10. Thus, for example,support layer 24 may comprise e.g. a film with thickness less than about12 microns, about 25 microns, about 38 microns, about 50 microns, or thelike.

If support layer 24 comprises a dense film, non-slip layer 14 may notnecessarily penetrate significantly thereinto. In other embodiments, asupport layer may comprise an at least partially penetrable web 22. Invarious embodiments at least partially penetrable web support layer 22may comprise any fibrous material including e.g. a nonwoven fibrouslayer such as a spunbonded web, a meltblown web, or a carded web; awoven web; a knitted cloth; a polymeric netting; or the like. In someembodiments (and as exemplified in FIG. 4) the material of non-sliplayer 14 may penetrate so completely into support web 22 as to result inweb 22 being partially, or completely buried (embedded) within thematerial of non-slip layer 14. FIG. 4 illustrates such an embodiment inwhich non-slip layer 14 is of such composition that it can be bondeddirectly to surface 12 a of backing 12. FIG. 5 illustrates an embodimentin which embedded support layer 22 is again present, but in which anadhesion-enhancing layer 20 is used to bond non-slip layer 14 to backing12.

Suitable materials for flexible backing layer 12 may include any of thematerials commonly used to make sandpaper including, for example, paper,cloths (cotton, polyester, rayon), polymeric films such as thermoplasticfilms, foams, and laminates thereof. The backing layer 12 will havesufficient strength for handling during processing, sufficient strengthto be used for the intended end use application, and the ability to havenon-slip layer 14 laminated to its first major surface, and make coat 16applied to its second major surface.

In the illustrated embodiment, backing layer 12 is formed of paper.Paper is a desirable material for backing layer 12 because it is readilyavailable and is typically low in cost. Conventional sandpaper, however,which has a paper backing layer, has limited durability, and has asmooth slippery surface that makes conventional sandpaper difficult tomove over a work surface and, therefore, makes sanding difficult. Paperbackings are available in various weights, which are usually designatedusing letters ranging from “A” to “F”. The letter “A” is used todesignate the lightest weight papers, and the letter “F” is used todesignate the heaviest weight papers.

In the illustrated embodiment of FIG. 1, backing layer 12 is continuous.That is, backing layer 12 does not contain holes, openings, slits,voids, or channels extending there through in the Z-direction (i.e. thethickness or height dimension) that are larger than the randomly formedspaces between the material itself when it is made. The backing may alsocontain openings (i.e. be perforated), or contain slits. Backing layer12 is also generally non-extensible. Non-extensible refers to a materialhaving an elongation at break of typically no greater than about 25%, nogreater than about 10%, or no greater than about 5%.

In certain embodiments, e.g. when backing layer 12 is formed of paper,backing layer 12 may be relatively thin, and typically has a thicknessof no greater than about 1.5 mm, no greater than about 1 mm, or nogreater than about 0.75 mm. In such embodiments, the backing layer 12 isgenerally not resilient. The backing layer 12 may be porous ornon-porous. In some embodiments, backing layer 12 consists of a singlelayer.

In some embodiments, backing layer 12 may be formed of a cloth materialor film, such as a polymeric film. Cloth materials may be desirablebecause they are generally tear resistant and are generally more durablethan paper and film materials. In addition, cloth backings toleraterepeated bending and flexing during use. Cloth backings are generallyformed of woven cotton or synthetic yarns that are treated to make themsuitable for use as a coated abrasive backing As is the case with paperbackings, cloth backings are available in various weights, which areusually designated using a letter ranging from “J” to “M” with theletter “J” designating the lightest weight cloth, and the letter “M”designating the heaviest weight cloths.

Suitable film materials for the backing layer 12 may include polymericfilms, including primed films, such as polyolefin film (e.g.,polypropylene including biaxially oriented polypropylene, polyesterfilm, polyamide film, cellulose ester film).

In various embodiments, backing layer 12 (as well as any other layers ofsandpaper 10) may be comprised of specially chosen materials, and/or maybe treated, so as to be easily foldable and/or tearable, e.g.hand-tearable. For example, one or more lines of weakness (e.g., a lineof partial- or through-perforations) may be provided to facilitate easyfolding and/or tearing by hand.

In general, any adhesive make coat 16 may be used to adhere the abrasiveparticles 18 to the backing layer 12. “Make coat” refers to the layer ofhardened resin over the backing layer 12 of the sandpaper 10. Suitablematerials for the adhesive make coat 16 include, for example, phenolicresins, aminoplast resins having pendant α,β-unsaturated carbonylgroups, urethane resins, epoxy resins, ethylenically unsaturated resins,acrylated isocyanurate resins, urea-formaldehyde resins, isocyanurateresins, acrylated urethane resins, acrylated epoxy resins, bismaleimideresins, fluorene-modified epoxy resins, and combinations thereof. Themake coat 16 may be coated onto the backing layer 12 by any conventionaltechnique, such as knife layer, spray layer, roll layer, rotogravurelayer, curtain layer, and the like. The sandpaper 10 may also include anoptional size coat (not shown). The make coat 16 and/or an optional sizecoat may contain optional additives, such as fillers, fibers,lubricants, grinding aids, wetting agents, thickening agents,anti-loading agents, surfactants, pigments, dyes, coupling agents,photo-initiators, plasticizers, suspending agents, antistatic agents,and the like. Possible fillers include calcium carbonate, calcium oxide,calcium metasilicate, alumina trihydrate, cryolite, magnesia, kaolin,quartz, and glass. Fillers that can function as grinding aids includecryolite, potassium fluoroborate, feldspar, and sulfur. The amounts ofthese materials are selected to provide the properties desired, as isknown to those skilled in the art.

In some embodiments, adhesive make coat 16 consists of a single layerthat is in direct contact with surface 12 b of backing layer 12. In suchembodiments, the combination of backing layer 12 and adhesive make coat16 does not encompass configurations involving three or more layers,e.g. a backing layer bearing a binder layer thereupon, which binderlayer bears an adhesive layer thereupon.

In general, abrasive particles 18 of any suitable size (e.g., diameteror equivalent diameter in the event of substantially nonsphericalparticles) may be used with this invention. In some embodiments,abrasive particles 18 may have a FEPA P grade, as outlined by theFederation of European Producers of Abrasives and as tested inaccordance with the ISO 6344 standard, of P100 or lower (with a lowergrade corresponding to larger particles). In various embodiments, theabrasive particles and the abrasive article comprising the abrasiveparticles, may comprise an FEPA grade of P80, of P60, or of P40.

Suitable abrasive particles may include, for example, fused aluminumoxide, heat treated aluminum oxide, alumina-based ceramics, siliconcarbide, zirconia, alumina-zirconia, garnet, emery, diamond, ceria,cubic boron nitride, ground glass, quartz, titanium diboride, sol gelabrasives and combinations thereof. The abrasive particles 18 can beeither shaped (e.g., rod, triangle, or pyramid) or unshaped (i.e.,irregular). The term “abrasive particle” encompasses abrasive grains,agglomerates, or multi-grain abrasive granules. The abrasive particlescan be deposited onto make coat 16 by any conventional technique such aselectrostatic coating or drop coating.

In general, abrasive article (sandpaper) 10 may be made by providing abacking layer 12 (e.g., a paper backing), coating an adhesive make coat16 on one major surface of the backing layer, at least partiallyembedding abrasive particles 18 in the make coat, thereby forming anabrasive surface, and laminating a non-slip layer 14 onto the firstmajor side of the backing layer opposite the make coat. These operationsmay be performed in any suitable order; the choice of the mostconvenient order and/or technique may depend e.g. on the particularconfiguration and materials of non-slip layer 14 and/or backing 12.

In cases in which non-slip layer 14 has suitable properties to behandled as a free-standing film or web (defined as meaning a film or webthat is not residing on a support layer 24 that is permanentlyincorporated into article 10, but not excluding that the film or web maybe delivered to a lamination process on a temporary liner, as disclosedelsewhere herein), non-slip layer 14 may be brought into proximity tothe first major side of backing 12 while in such free-standing form, andlaminated thereto. If non-slip layer 14 has a composition thatfacilitates bonding directly to surface 12 a of backing 12, layer 14 maybe bonded directly thereto, e.g. producing a structure of the generaltype illustrated in FIG. 1. Alternatively, an adhesion-enhancing layer20 may be used to enhance, or to perform, the adhering of non-slip layer14 to backing 12, e.g. producing a construction of the general typeexemplified in FIG. 2. Layer 20 may comprise an adhesion-promoting layer(e.g. a primer layer, tie layer, or the like) which might be appliede.g. to major surface 12 a of backing layer 12, to major surface 14 b ofnon-slip layer 14, or both. In some instances, layer 20 may comprise anadhesive layer, e.g. a laminating adhesive (whether thermoactivatable,or a pressure-sensitive adhesive). If desired, multipleadhesion-enhancing layers 20 (e.g., one or more adhesive layers and oneor more tie or primer layers) may be used.

By way of other examples, in order to make an article 10 e.g. of thegeneral type illustrated in FIG. 3, in which non-slip layer 14 isprovided as part of a multilayer structure comprising a support layer 24(which multilayer structure is laminated to backing 12), non-slip layer14 may first be deposited or formed upon support layer 24 by anysuitable method. For example, non-slip layer 14 may comprise anysuitable hot melt coatable, solvent-born, water-borne, or polymerizablecomposition, which may be deposited (e.g., coated) upon support layer24. This process may be performed in-line with the laminating of theresulting multilayer structure to backing 12; or, the multilayerstructure may be rolled up and stored until laminated to backing 12 in aseparate operation. The coating of non-slip material upon support layer24 may be performed by any suitable method. For example, the materialsmaking up non-slip layer 14 may collectively comprise a hot-meltcoatable, 100% solids mixture (e.g., with little or no solvent, water,etc.). The material of non-slip layer 14 may be hot-melt coated ontosupport layer 24 using, for example, roll coating, hot melt coating,spray coating, drop die coating, etc. In one embodiment, a roller usedto apply the coatable non-slip material is a foam roller, which mayimpart a surface texture to the non-slip layer. Alternatively, a foamroller may be used to post treat the non-slip layer 14 after it has beencoated onto support layer 24, thereby imparting the non-slip layer witha surface texture.

In another approach, an aqueous emulsion or aqueous dispersion of anon-slip coating material may be coated onto support layer 24. Inanother approach, a solution (e.g., in an organic solvent or solventmixture) of a non-slip coating material may be coated onto support layer24 and the solvent evaporated. In still another approach, a non-slipcoating material precursor (e.g., comprising a mixture of polymerizablecomponents that may be reacted so as to form the non-slip coating) maybe coated onto support layer 24 and caused to react, causing theprecursor to be transformed into the non-slip coating.

The multilayer structure comprising support layer 24 and non-slip layer14 coated thereupon may be laminated to the first major side of backing12 (with major surface 14 a of non-slip layer 14 facing outward) by anysuitable method. For example, in the exemplary embodiment shown in FIG.3, a laminating adhesive 20 may be used to bond to major surface 24 b ofsupport layer 24 and to major surface 12 a of backing 12. In embodimentsin which support layer 24 is of suitable composition to serve as anadhesive layer, surface 24 b of support layer 24 may be bonded directlyto major surface 12 a of backing 12.

In some cases, it may be convenient to deliver non-slip layer 14 (or amultilayer construction of non-slip layer 14 and support layer 24) tothe lamination process, on a temporary supporting liner 26 asexemplified in FIG. 6. Such a temporary supporting liner may beseparated from non-slip layer 14 and discarded (or re-used) oncenon-slip layer 14 is laminated in place on the first major side ofbacking 12. (FIG. 6 shows abrasive sheet 10 with temporary support liner26 partially removed). Optionally, liner 26 may be retained in place,either during the rolling up of abrasive article 10 as a roll good, oreven after abrasive article 10 is separated (cut) into individual sheetsof sandpaper, in which case it may be removed by an end user prior tothe use of the sheets of sandpaper. Although not shown in FIG. 6, atemporary supporting liner 26 may also be used in the case that non-sliplayer 14 is supported on a support layer 24 that becomes part of finalproduct 10. In fact, it may be convenient to use a temporary supportliner 26 in any of the configurations and embodiments disclosed herein.

By way of still further example, constructions of the general typeexemplified in FIGS. 4 and 5 may be made by depositing the material ofnon-slip layer 14 (e.g., as a molten, solvent-borne, or water-bornematerial) onto support web 22. The material of non-slip layer 14 maythen flow at least partially into the interior of support web 22. In theparticular exemplary embodiments of FIGS. 4 and 5, this was performedsuch that support web 22 is completely buried within major surface 14 aand 14 b of non-slip layer 14. However, this does not necessarily haveto be the case. In some embodiments, first major surface 22 a of supportweb 22 may protrude at least partially through portions of major surface14 a of non-slip layer 14, as long as such protruding portions ofsupport web 22 do not unacceptably affect the non-slip properties ofnon-slip layer 14. Likewise, in some embodiments, second major surface22 b of support web 22 may protrude at least partially through portionsof major surface 14 b of non-slip layer 14, as long as such protrudingportions do not unacceptably affect the ability of non-slip layer 14 tobond (either directly to surface 12 a of backing 12 in the configurationof FIG. 4, or to surface 20 a of adhesion-enhancing layer 20 in theconfiguration of FIG. 5).

In general, non-slip layer 14 may be provided on backing 12 according toany suitable procedure and configuration described herein. That is,layer 14 may be bonded directly to backing 12 if its compositionfacilitates this. Or, non-slip layer 14 may be provided on the firstmajor side of backing 12, by use of any convenient combination of theherein-disclosed adhesion-enhancing layers (whether adhesive layers oradhesion-promoting layers, or both), and/or support layers. In someembodiments, the only layer present between non-slip layer 14 andbacking 12 is an adhesive layer. In other embodiments, exactly oneadhesive layer and exactly one adhesion-promoting tie layer or primerlayer are present between non-slip layer and backing 12. In otherembodiments, exactly one support layer and exactly one adhesive layerare present between non-slip layer 14 and backing 12. In still otherembodiments, exactly one support layer, exactly one adhesive layer, andexactly one adhesion-promoting tie layer or primer layer, are presentbetween non-slip layer 14 and backing 12.

In general with regard to the herein-discussed lamination processes, bylamination is meant bonding of sheet-like substrates or layers to eachother, as achieved by bringing the surfaces of the layers (or anyadhesion-enhancing layer as might be present thereon, as discussedelsewhere herein) into contact with each other, optionally facilitatedby heat and/or pressure, e.g. depending on the type of adhesive andbonding mechanism. For example, if non-slip layer 14 comprises aheat-bondable composition, and/or if adhesion-enhancing layer 20comprises a heat-bondable composition, the laminating process maycomprise heating the compositions up to appropriate temperatures e.g. byplacing the layers between one or more pairs of heated surfaces (e.g.,of nip rollers or of heated platens) that press the layers against eachother. If adhesion-enhancing layer 20 comprises a pressure-sensitiveadhesive composition, such pairs of pressing surfaces (e.g. nip rolls)may still be used; however the laminating process may not necessarilyrequire significantly elevated temperatures (although at least someslightly elevated temperature may be preferred in order to promoteoptimal wet-out of the pressure-sensitive adhesive).

In many cases, it may be convenient to provide at least backing 12 as aroll good, and likewise to provide at least non-slip layer 14 (or, amultilayer construction comprising at least non-slip layer 14 and asupport layer 24) as a roll good, and to perform the lamination by wayof passing the components through one or more pairs of nip rollers, aswill be familiar to those of ordinary skill. However, if desireddiscrete sheets rather than roll goods may be used; such sheets may bepassed piecewise through nip rolls, or may be laminated between(non-rotating) platens, again as will be familiar to those of ordinaryskill.

In many instances, it may be convenient to provide backing layer 12,make coat 16, and abrasive particles 18 in the form of a pre-formed(i.e. otherwise complete) abrasive sheet (whether discrete sheets or asa roll good) and then laminate non-slip layer 14 thereto, by any of themethods disclosed above.

Any suitable pre-formed abrasive (whether sheet or roll good) may beused, comprising a wide variety of commercially available conventionalsandpaper constructions having a wide variety of backing materials (e.g.papers, films, cloths), weights (e.g. A, B, or C weight paper), andabrasive particles. Representative examples of suitable pre-formedabrasive articles include various products available from 3M Company(e.g., under the Sand Blaster or Pro Grade trade designations) with FEPAratings ranging from e.g. P40 to P2500.

In a specific embodiment, sandpaper 10 as disclosed herein may beprovided to an end user as a standard 9×11 inch sheet. In otherembodiments, the sandpaper 10 may have a width of about 3 to about 4inches, or of about 5 to about 6 inches, and a length of about 8 toabout 10 inches, or about 10 to about 12 inches. In another aspect, thepresent invention provides a package of sandpaper including a stack ofsheets of sandpaper. The stack may include at least 2 sheets, at leastabout 6 sheets, or at least about 10 sheets. Optionally, disposableliners, protective films, etc. may be provided in between the sheets, ifdesired. In some embodiments, sandpaper 10 may be provided to an enduser as a roll good which may be used in this form or from whichindividual sheets may be separated as desired.

In some end use applications, the sheet-like abrasive article (e.g.,sandpaper)10 may be used for hand sanding a work surface, such as awooden surface or work piece. That is, the abrasive article 10 may beused to remove material from a surface by holding the abrasive article10 directly with one's hand (i.e. without the aid of a tool, such as asanding block), and moving the abrasive article 10 against the worksurface. Thus in this context hand sanding is distinct from operationsin which sandpaper is held and motivated by a device such as a polishingshoe, vibrating or orbital sander, and the like. However, it will berecognized that the abrasive articles disclosed herein may also be usedwith manually-operated sanding tools and sanding blocks, or with poweredequipment, as may be desired.

In use, users may often fold an abrasive article (e.g., sandpaper),thereby producing sheets that are easier to handle by hand. Folding thesandpaper, however, may weaken the sandpaper along the fold line,particularly if, during sanding, the sections of the folded sandpaperslip relative to each other so that the fold line traverses (moves)along the sandpaper. Such moving of a fold line along an abrasivearticle may e.g. cause the backing to weaken, crack, etc. over portionsof the article, and may thus reduce the working life of the abrasivearticle. It has been discovered that the use of a non-slip layer on thefirst major side of an abrasive article may minimize or prevent suchslippage from occurring. That is, in hand sanding with an abrasive sheetthat is folded upon itself so that areas of the non-slip layer of thearticle first major side are adjacent each other in closely facingrelation, even in the presence of loose particulates the non-slip layerareas may be able to maintain contact with each other, and to resistslipping relative to each other, so that the sheet remains largely inthe originally folded configuration rather than the areas slippingrelative to each other such that the fold in the sheet traverses alongthe sheet. This may be advantageous and may e.g. prolong the workinglife of the abrasive sheet. Such discoveries, and further details ofnon-slip layers, are discussed in further detail in U.S. PatentApplication Publication 2009/0325470 to Petersen, entitled SandpaperWith Non-Slip Coating Layer, which is incorporated by reference in itsentirety herein.

In some instances, (e.g., with particularly coarse grades of sandpaper,e.g., with FEPA grades of P100, P80, P60, or P40, and/or in situationsin which large amounts of particulate debris may be present), it may beadvantageous for non-slip layer 14 to comprise certain compositions,e.g. chosen from those comprising at least one base resin and at leastone tackifying resin. Such compositions and uses thereof are describedin further detail in U.S. Provisional Patent Application Ser. No.61/451,680 to Petersen et al., filed Mar. 11, 2011, entitled SandpaperWith Non-Slip Layer, and in U.S. Provisional Patent Application Ser. No.61/451,678 to Petersen et al., filed Mar. 11, 2011, entitled CoarseSandpaper With Non-Slip Coating layer, both of which are incorporated byreference in their entirety herein.

In some cases, laminated non-slip layer 14 may comprise a fibrous layeras mentioned herein. Further details of such laminated fibrous non-sliplayers (as well as other configurations of fibrous non-slip layers) aredescribed in further detail in U.S. Provisional patent application Ser.No. ______ (Attorney Docket No. 67614US002) to Petersen, filed evendatewith the present application, and entitled Sandpaper With FibrousNon-Slip Layer, and which is incorporated by reference in its entiretyherein.

It will be apparent to those skilled in the art that the specificexemplary structures, features, details, configurations, etc., that aredisclosed herein can be modified and/or combined in numerousembodiments. All such variations and combinations are contemplated bythe inventor as being within the bounds of the conceived invention.Thus, the scope of the present invention should not be limited to thespecific illustrative structures described herein, but rather extends atleast to the structures described by the language of the claims, and theequivalents of those structures. To the extent that there is a conflictor discrepancy between this specification and the disclosure in anydocument incorporated by reference herein, this specification willcontrol.

List of Exemplary Embodiments Embodiment 1

A sheet of sandpaper, comprising: a flexible backing layer havingopposed first and second major sides; an adhesive make coat on thesecond major side of the backing layer; abrasive particles at leastpartially embedded in the make coat, thereby defining an abrasivesurface; and an exposed laminated non-slip layer of less than about 600microns in thickness, on the first major side of the backing layer.

Embodiment 2

A sheet of sandpaper as defined in embodiment 1, wherein the non-sliplayer is in direct contact with a first major surface of the first majorside of the flexible backing layer.

Embodiment 3

A sheet of sandpaper as defined in embodiment 1, further comprising atleast one support layer at least a portion of which is between at leasta portion of the non-slip layer and a portion of the backing layer.

Embodiment 4

A sheet of sandpaper as defined in embodiment 3, wherein the non-sliplayer is a hot-melt coating layer on the support layer.

Embodiment 5

A sheet of sandpaper as defined in any of embodiments 1-2, wherein thenon-slip layer comprises an embedded support layer.

Embodiment 6

A sheet of sandpaper as defined in any of embodiments 1 and 3-5, furthercomprising at least one adhesion-enhancing layer at least a portion ofwhich is between at least a portion of the non-slip layer and a portionof the backing layer, wherein the adhesion-enhancing layer is chosenfrom the group consisting of a primer layer, a tie layer, and apressure-sensitive adhesive layer.

Embodiment 7

A sheet of sandpaper as defined in any of embodiments 1-6, wherein thenon-slip layer has an average tack level, as measured by ASTM D2979-88using a 10 second dwell time, and a probe removal speed of 1 cm/s of nogreater than about 250 grams.

Embodiment 8

A sheet of sandpaper as defined in any of embodiments 1-7, wherein thenon-slip layer has an average peak static coefficient of friction of atleast about 1 gram when measured according to ASTM D 1894-08.

Embodiment 9

A sheet of sandpaper as defined in any of embodiments 1-8, wherein thenon-slip layer has a thickness of less than about 100 microns.

Embodiment 10

A sheet of sandpaper as defined in any of embodiments 1-9, wherein thenon-slip layer comprises a generally planar exposed outer surface.

Embodiment 11

A sheet of sandpaper as defined in any of embodiments 1-10, wherein thenon-slip layer comprises an amorphous base resin, and an effectiveamount of a tackifying resin.

Embodiment 12

A method of making a sheet of sandpaper having a laminated non-sliplayer on the first major side thereof, comprising the steps of:providing a flexible backing layer having opposed first and second majorsides; coating an adhesive make coat on the second major side of thebacking layer; at least partially embedding abrasive particles in themake coat, thereby forming an abrasive surface; and, laminating anon-slip layer onto the first major side of the backing layer to form anexposed laminated non-slip layer of less than about 600 microns inthickness on the first major side of the backing layer.

Embodiment 13

The method of embodiment 12 wherein the non-slip layer is laminateddirectly to a first major surface of the first major side of the backinglayer with no other layers being therebetween.

Embodiment 14

The method of embodiment 12 wherein one or more adhesive layers areprovided between at least a portion of the non-slip layer and a portionof the backing layer.

Embodiment 15

The method of any of embodiments 12 and 14 wherein one or more tielayers or primer layers are provided between at least a portion of thenon-slip layer and a portion of the backing layer.

Embodiment 16

The method of any of embodiments 12 and 14-15 wherein the non-slip layeris provided on a support layer at least a portion of which, after thelamination is completed, is positioned between at least a portion of thenon-slip layer and at least a portion of the backing layer.

Embodiment 17

The method of any of embodiments 12 and 14-16 wherein the non-slip layeris delivered to the first major side of the backing layer while residingon a temporary liner, and wherein the temporary liner is separated fromthe non-slip layer after the lamination is completed.

Embodiment 18

A method of hand sanding a work surface comprising the steps of:providing a sheet of sandpaper as defined in any of embodiments 1-11;manually engaging the laminated non-slip layer with a human hand; andmanually moving the sandpaper in a plurality of directions over the worksurface.

Embodiment 19

A method of hand sanding a work surface comprising the steps of:providing a sheet of sandpaper made by a method as defined in any ofembodiments 12-17; manually engaging the laminated non-slip layer with ahuman hand; and manually moving the sandpaper in a plurality ofdirections over the work surface.

1. A sheet of sandpaper, comprising: a flexible backing layer havingopposed first and second major sides; an adhesive make coat on thesecond major side of the backing layer; abrasive particles at leastpartially embedded in the make coat, thereby defining an abrasivesurface; and an exposed laminated non-slip layer of less than about 600microns in thickness, on the first major side of the backing layer.
 2. Asheet of sandpaper as defined in claim 1, wherein the non-slip layer isin direct contact with a first major surface of the first major side ofthe flexible backing layer.
 3. A sheet of sandpaper as defined in claim1, further comprising at least one support layer at least a portion ofwhich is between at least a portion of the non-slip layer and a portionof the backing layer.
 4. A sheet of sandpaper as defined in claim 3,wherein the non-slip layer is a hot-melt coating layer on the supportlayer.
 5. A sheet of sandpaper as defined in claim 1, wherein thenon-slip layer comprises an embedded support layer.
 6. A sheet ofsandpaper as defined in claim 1, further comprising at least oneadhesion-enhancing layer at least a portion of which is between at leasta portion of the non-slip layer and a portion of the backing layer,wherein the adhesion-enhancing layer is chosen from the group consistingof a primer layer, a tie layer, and a pressure-sensitive adhesive layer.7. A sheet of sandpaper as defined in claim 1, wherein the non-sliplayer has an average tack level, as measured by ASTM D2979-88 using a 10second dwell time, and a probe removal speed of 1 cm/s of no greaterthan about 250 grams.
 8. A sheet of sandpaper as defined in claim 1,wherein the non-slip layer has an average peak static coefficient offriction of at least about 1 gram when measured according to ASTM D1894-08.
 9. A sheet of sandpaper as defined in claim 1, wherein thenon-slip layer has a thickness of less than about 100 microns.
 10. Asheet of sandpaper as defined in claim 1, wherein the non-slip layercomprises a generally planar exposed outer surface.
 11. A sheet ofsandpaper as defined in claim 1, wherein the non-slip layer comprises anamorphous base resin, and an effective amount of a tackifying resin. 12.A method of making a sheet of sandpaper having a laminated non-sliplayer on the first major side thereof, comprising the steps of:providing a flexible backing layer having opposed first and second majorsides; coating an adhesive make coat on the second major side of thebacking layer; at least partially embedding abrasive particles in themake coat, thereby forming an abrasive surface; and, laminating anon-slip layer onto the first major side of the backing layer to form anexposed laminated non-slip layer of less than about 600 microns inthickness on the first major side of the backing layer.
 13. The methodof claim 12 wherein the non-slip layer is laminated directly to a firstmajor surface of the first major side of the backing layer with no otherlayers being therebetween.
 14. The method of claim 12 wherein one ormore adhesive layers are provided between at least a portion of thenon-slip layer and a portion of the backing layer.
 15. The method ofclaim 12 wherein one or more tie layers or primer layers are providedbetween at least a portion of the non-slip layer and a portion of thebacking layer.
 16. The method of claim 12 wherein the non-slip layer isprovided on a support layer at least a portion of which, after thelamination is completed, is positioned between at least a portion of thenon-slip layer and at least a portion of the backing layer.
 17. Themethod of claim 12 wherein the non-slip layer is delivered to the firstmajor side of the backing layer while residing on a temporary liner, andwherein the temporary liner is separated from the non-slip layer afterthe lamination is completed.